1. Technical Field
This invention relates in general to a method for monitoring the status of a telephone by an associated processor and in particular to methods which permit the telephone to interrupt the processor in response to a change in status thereof. Still more particularly, the present invention relates to methods which automatically generate a single interrupt message in response to either a change in telephone status or the termination of a selected time period.
2. Background Art
It is well known in the prior art to utilize computer program controlled telephone switching systems to interconnect individual telephone stations, digital terminals, personal computers and large main-frame computers. Such intercommunications may be utilized to provide voice and/or data communications. In a typical application, the telephone switching system is utilized to establish communication connections between two communication stations, both of which may included an associated computer facility connected to a communications pair. Thereafter, the operator generally utilizes a modem which converts digital signals output by a computer to analog signals suitable for transmission by the telephone system. Alternately, certain systems permit direct communication by digital signals over special communication pairs.
More recently, certain systems have been proposed which incorporate computer facilities which are directly connected to a communications pair. In such systems, the computer facility is utilized to emulate the functions of a telephone communication system. In this manner, the telephone communication station is no longer required for computer data call origination purposes.
In the first of the aforementioned systems it is desirable for the associated computer facility to be able to monitor the status of the associated communication station or telephone. This is generally accomplished by one of two methods. In a first method, the processor associated with the telephone must selectively and continuously "poll" the status of the telephone to determine whether or not a change in status has occurred. This technique is quite wasteful of processor time and makes it difficult for the processor to perform additional tasks.
A second technique whereby telephone status changes may be monitored by an associated processor involves the continuous interruption of the processor by the telephone in response to each and every change in telephone status. While this technique is less wasteful of processor time it also does not permit the processor to effectively perform additional tasks due to the repeated interruptions which telephone status changes generate.
It should therefore be apparent that a need exists for an efficient method whereby changes in telephone status may be indicated to an associated processor.